Apparatus for balancing rotatable bodies



June 30, 1936. J, LUNDGREN APPARATUS FOR BALANCING ROTATABLE BODIES 8 Sheets-Sheet 1 Filed May 16, 1951 uwE/v MK I 7WZM ArroRA/Ex' June 30, 1936- J. LUNDGREN 2,046,294

APPARATU FOR BALANCING ROTATABLE BODIES Filed May 16, 1931 8 Sheets-Sheet 2 Filed May 16, 1931 8 Sheets-Sheet 3 HIM.

U/n-NroR.

A TTORNE].

June 30, 1936. J. LUNDGREN 2,046,294

APPARATUS FOR BALANCING ROTATABLE BODIES Filed May 16, 1931 8 Sheets-Sheet 5 v l lllllll 'A ffOR/VEY.

June 30, 1936. J 'LUNDGREN 2,046,294

APPARATUS FOR BALANCING ROTATABLE BODIES Filed May 16, 1931 8 Sheets-Sheet 6 6 Z9! g I i Ii AK i I 1 .ILIIIL J 4 02. //v. H '[401m 2- /0 02-101.

x: 2 Y: 8 1' IV INVENTOR. j LEFT me H r fiM M I ATTORNEY.

June 30., 1936. j LUNDGREN 2,046,294

APPARATUS FOR BALANCING ROTATABLE BODIES Filed May 16, 1931 8 Sheets-Sheet 7 17mg) www- INVENTOR.

wflm mk BY ATTORNEY.

June 30, 1936.

J. LUNDGREN APPARATUS FOR BALANCING ROTATABLE BODIES Filed May 16, 1931 8 Sheets-Sheet 8 I l/vvs/vrog, 4

774M Afro/15y,

atented June '30, 1936 rat APPARATUS FOR BALANCING ROTATABLE BODEES Jacob Lundgren, Philadelphia, its, assignor to Tinius Olsen Testing Machine Company, Philadelphia, Pa., a corporation of Kennsylvania Application May 16, 1931, Serial No. 53?,848 11 Claims. (or. i3-5l) The object of this invention is to devise a novel apparatus for'balancing rotatable bodies wherein a centrifugal high-tension spark principle is employed, and wherein the angular indication, as well as the amount of unbalance, are taken while the machine is in operation. All readings for unbalance are taken without reversing the part to be balanced in the balancing machine.

A further object of the invention is to devise novel compensating means for the unbalance of the specimen which is electrically controlled and positioned at the will of the operator to determine the amount of unbalance, the angle of unbalance being also determined and visibly indicated on a graduated angle indicator.

A further object of the invention is to devise a novel balancing machine which can be operated at a constant definite speed differing from critical speed, thereby eliminating the necessity of maintaining critical speed or passing through critical speed.

A further object of the invention is to devise a novel balancing machine which will operate ata comparatively low speed, and thereby permit the accurate determination of unbalance 'while holding to a minimum the centrifugal forces which might deflect the parts being balanced.

With the above and other objects in view, as

will hereinafter more clearly appear, my invention comprehends a novel apparatus for balancing rotatable bodies.

' It further comprehends a novel balancing machine wherein provision is made for electrically positioning, at the will of the operator, a compensator weight to compensate for the unbalance in a specimen under test, the machine being so constructed that at the same time it will visibly indicate the angle of unbalance, so that the angle and amount of unbalance in two different planes of the specimen can be determined without reganization of these instrumentalities as herein set forth.

Figure 1 is a perspective view of a balancing machine embodying my invention. q

Figure 2 is a perspective view of the machine, viewed from a different angle to that of Figure 1.

Figure 3 is a top plan view, partly broken away and partly in section, showing more particularly the compensating means.

Figure 4 is an end view, partly in section, showing more particularly the manner in which the housing of the compensating means is revolubly carried by a shaft. Y

Figure 5 is an end elevation of a portion of the machine, certain of the parts being broken away for the sake of clearness of illustration.

Figure 6 is a sectional elevation, the section being taken substantially on line 6-6 of Figure '7.

Figure '7 .is a section on line 1-1 of Figure 6.

Figure 8 is a front elevation of certain portions of the compensating mechanism.

Figure 9 is a side elevation of the guiding mechanism for a specimen.

Figure 10 is a wiring diagram.

Figure 11 is a sectional view of a. portion of Figure 6.

t Figure 12 is Figure 6.

a side elevation of a portion of Figure 13 is a reading diagram.

Similar numerals of reference indicate corresponding parts.

Referring to the drawings:

i designates the base of a balancing machine embodying my invention. The machine can be placed directly on a floor, as free as possible from vibration, or on a cement foundation and can be bolted down to the foundation, or it can be provided with support pads 2, and levelled by set screws 3, provided at the four corners of the base. The base i is provided with the longitudinally extending front and rear guides 4, on which the base plates 5 of vertical spring supports 6 are longitudinally adjustable.

"the upwardly extending vibration rods 9, fixed to their base plate 5, and connected by means of rods l2, to. a rigid frame l3, which is formed by the side rods l4, connected together by the cross bars l5. The rods 4 are tubular and their free ends are preferably covered by the caps l6, secured to the frame in any desired manner. The rods l2 extend into the apertures in the bolts H which pass through the cross bars I 5 and are fixed in position by means of nuts l6. The rods l4 of the rigid frame have longitudinally adjustable on them the roller supporting cross bars i9, in which the shoes26 of-the roller brackets 2| are adjustable. The brackets 2| are fixed in their adjusted position by nuts 22. The brackets 2| carry the rollers 23 which are free to revolve and serve as bearings for supporting the specimen which is to be tested. I

In many cases, the parts or specimens to be balanced can be balanced on two bearings, but, in some cases, it is advantageous to employ a center guide to insure against error in balancing, due to deflection or misalignment of the part to be balanced. Some classes of work, such as,

straight-line-8 type crank shafts, long rolls for printing'presses or paper machines, and similar parts, may change their shape and become. misaligned while being handled during the manufacturing process or during transportation. If such misaligned parts are tested for balance while only supported on two bearings, accurate and true balancing may be difficult or impossible. The same condition exists when the part to be balanced is structurally weak and is supported in only two bearings during the balancing operation. I have, therefore, found it advantageous in many cases to provide a center guide in the form of'a bar 24 which is pivotally mounted at one end as at 25, to the upwardly extending rear portion of a bracket 26 which is provided with collars slidably mounted on the rods M of the rigid frame. Guide rollers 21, journalled in blocks 28, are relatively adjustable on the upper horizontal stretch of the bar 24 and are secured in fixed position by means of fastening devices 26 of-any desired character. The bar at its central portion is preferably upwardly deflected, as at 69, in order to provide properclearance between it and the specimen which is to be tested. The free end of the bar 24 is slotted to receive the threaded rod 3| which is pivoted at 32 to an upward extension to the front end of the bracket 26 and a knurled nut 33 is provided to a pivotal connection at either the right or left hand end of the machine. As this lockingmechanism is the same at each end, a detailed description of one will suilice for both. The post 6 carries at its upper end a gear case 35, see Figure 5, in which is journalled a shaft 36 pm- 'the same as that shown in my prior Patent vided with an actuating handle 61 and with a pinion 66 which meshes with a rack 39 on a rod 46 which carries a ball shaped pivot member 4| which is flanged at its bottom and secured to the rod 40 by means of a cap nut 42 in thread- 5 ed engagement with 1 such rod 46. The iuxtaposed crossbar |5,of the rigid frame is provided with an aperture 43 opening through its bottom into which the pivot member 4| may extend. No claimis made in this case to the pivot locking means as this is claimed in my copending application, Serial 620,258, filed June 30, 1932.

1 One of the posts ill, of each spring support unit 6, is-provided with a fitting 44, with which a contact rod 45 is in threaded engagement, the forward end of said rod forming a movable contact which cooperates with a spring contact 46 carried by a stop 41, depending from a cross bar I5. The contact rod 45 is provided with an actuating handle 46.

The rods l4 have slidably mounted on them a base plate 49 which carries a casing 50 within which a shaft 5| is journalled, see Figure 6, said shaft having fixed to it a pulley 52 around which passes a belt 56, said belt also passing around a pulley on the shaft of an electric motor, not shown. This pulley is provided with a face plate 54 adapted to be connected in any desired manner with the specimen 55 which is to. be revolved. As

shown, the face plate is connected by driving pins 30 with a flange on the crank shaft. As illustrated,

I have shown the specimen under test as being a crank shaft for an internal combustion engine, it being of course understood that any desired type of specimen .which can be received on the roller bearings can be tested in the type of machine here under discussion. r

The shaft 5|, see Figure 6', has mounted on it a spiral gear 56 which meshes with a spiral gear 51, suitably supported and operatively connected with a dial shaft 56, see Figure 2, to effect the revolution of a dial hand 59 so that this dial hand 59 revolves at a predetermined speed relative to the speed of revolution of the specimen 55 which is being tested. The dial hand 59 has its free end in proximity to a metallic ring 60 fixed to an insulating member 6| which is graduated in degrees as at 62. As the graduated dial, the dial hand, and the drive for the dial hand is substantially 1,860,257, May 24, 1932, I have deemed it unnecessary to describe in detail thisconstructionas my present invention is more particularly directed to the novel compensating device and its control. The cross bars l9 are provided with split collars slidable on the rods I4 and are clamped in their adjusted position by means of fastening devices 63. In a similar manner the bracket 26 is fixed in its adjusted position by means of fastening devices 64, the collars being split and clamped together by such fastening devices.

The compensating mechanism The motor driven shaft 5|, see Figure 6, is provided with a reduced diameter on which is fixed thehub of a friction wheel 66. It is also provided with areduced diameter 61 on which is loosely mounted the hub of a friction wheel 66 which is of greater diameter than the diameter of the friction wheel 66, the purpose being to obtain a variable friction drive for the compensating mechanism. The friction wheel 66 is also provided with an annular friction face 66 which is of less diameter than the diameter of the friction wheel 66. The friction wheel 66 is provided with aninner aoeaaee facing of friction material I8 secured thereto by fastening devices II. The friction wheel 58 has secured thereto the electromagnets I2 which are circumferentially spaced from each other, four of these electromagnets being employed as will be understood by reference to Figure '7. The armature I3 of the electromagnets is adapted at its outer marginal portion to engage the friction face formed by the material I8, and this engagement is maintained due to the provision of the springs I8 which encircle the studs 15 which are secured to the friction wheel 86. These studs at their free ends are of reduced diameter and pass through the apertures IS in the armature I3; and shoulders II are formed on these studs which limit the movement of the armature I3 towards the poles of the electromagnets 12. The friction wheel 88 is retained in assembled position on the shaft 5i by means of a collar I8. A pair of friction wheels I9 and I88 are adapted to cooperate with the friction wheel 66. These friction wheels 79 and I85 are loosely mounted at opposite ends of a cross bar 88 which is fixed on a rock shaft 8|, carried by one of the brackets 82. The rock shaft 8! has fixed to it the armature 83 which cooperates with the opposed electromagnets 8,4 and 85, see Fig ure 7. The armature 83, at its lower end, is provided with a recess 88 into which the free end 'of a spring 87 extends, the opposite end of said spring being secured by fastening devices 88 to the base plate 49 which carries the compensating mechanism and is provided with collars clamped on the rods I i. The rock shaft 8| has also fixed to it a bar 89 which carries the front friction roller 98 and the rear friction roller 9|, see Figures 6 and 12, the roller 98 cooperating with the friction face 92, of the friction wheel 68; while the roller 9i cooperates with the friction face 89, of the friction wheel 88, it being-noted that these friction wheels are offset from each other. The friction wheels 19. and 98 are connected by a common hub to rotate in unison, and in a similar manner the friction wheels |86 and 9| are connected by a common hub to rotate in unison.

The friction wheel 68 is provided with a' pin 93 secured to it and extending into a recess larger than such pin, in a collar 99, on a shaft 95, suitably journalled. A second pin 96 is also preferv ably employed fixed to the friction wheel 68 and passing into an enlarged aperture 97 in the collar 95 so that the pin 93 is counterbalanced.

t will be understood that I employ two electro magnets 89 and two electromagets 85. When the electromagnets 84 are energized the friction wheels 19 and 98 are brought into engagement with their respective friction wheels 65 and I58, and when the electromagnets 85 are energized the friction wheels I86 and 9I will be broug'htinto frictional engagement with the friction'wheels 98 and 69 respectively.

The shaft 95 is journalled in bearings 98, see Figure 2, and loosely mounted on this shaft is a yoke 99, see Figures 2, 3 and 8, and this yoke has depending from it the plate armature I88 which cooperates with the opposed electromagnets IIII and I02, there being two electromagnets IIII and two electromagnets I82. The armature I88 is recessed at its lower end I'S at I83, to receive the free end of a spring I89 which is secured by means of fastening devices I85 to the base plate 99. The shaft 95 is provided with a coupling I89 in which is fixed a carrier I81 so that the latter will revolve in unison with the revolution of the shaft 95 and this carrier is fixed in position by means of the fastening devices I88, see Figure 4.

One arm of the yoke 99 has fixed to it, by means of fastening devices I89, a bevelled friction driving wheel H8. In a similar manner the other arm of the yoke has fixed to it, by means of fastening devices I I I, a beveled friction driving wheel H2. be moved into engagement at the will of the operator with a bevelled friction wheel II3 which is fixed to a cap sleeve II I provided with a hub in which one end of a screw I I5 is fixed by means 10 of a pin IIS. The opposite end of this screw H5 is journalled in an end closure II'I closing the end of the cylinder which forms the carrier I81. and fixed thereiniby means of fastening devices II8. The screw H5 has fixed .to it a gear H9 15 which meshes with a, gear I28 fixed on a stud shaft IZI, said stud shaft having also fixed on its gear I22 which meshes with a gear I23, on the hub of a cap I29 which is journalled on the screw I5. The cap I28 is graduated as at I25, go around its periphery. A collar I28 is fixed to the screw M5 by means of a. pin'IZ'I and retains the cap I28 in position. It will be understood that the cylinder I8I is in fixed relation with the shaft 95 and it is provided with a slot I28 and 25 along one side of this slot are the graduations I29.

These wheels H8 and II? are adapted to I38 designates a compensating weight to'which is fixed a shoe I3I which travels in the slot I28 and is provided'with a single graduation I32 30 which is adapted to. be brought into registration with the graduations I29 during the operation. The compensating weight at opposite ends has the projecting pins I33 which limit the travel of the compensating weight I38 in either direction by contacting with stops I81 and-I93. The stop I8! is carried by the hub of the cap sleeve I I4 and extends into a grooved collar I89 similar to the collar III and closing one end of the carrier I81. The collar I89 is provided with an aperture I98 40 into which the juxtaposed pin I33 may pass into the path of the stop I8'I. of the carrier I81 the collar H1 is provided with ah aperture I9I through which the juxtaposed pin I33 of the compensating weight I38 may pass 45 into the annular groove I92 into which extends the stop I93 carried by the gear I28. This weight I 30 is in threaded engagement with the screw I I5.

At the opposite end The shaft 95, see Figure 3, has fixed to it a collar I39 against which is adapted to be fixed an insulating collar I35 having in its periphery a contact I 35. cured in position by means of a set-screw I31 which is in threaded engagement with the shaft 95, a suitable washer I38 being provided. A screw I39 is in threaded engagement with an actuating handle I98 and is mounted onlthe base plate 49. This screw I39 passes through the base of a spring contact blade ISI which bears against the periphcry of the insulating collar I35, so. that during each revolution of the shaft 95 contact will be made. with the contact I38. By loosening the screw I3? the position of the contact I36 can be circumferentially adjusted.

This insulating collar I35 is se- It willbe seen from Figure 1 that the base I of the machine has rising from it the standards I42 which carry the table I93 on which are mountedthe electrical controls. which is used when the left end of the vibratory bed is locked and the right end is free to vibrate, and I45 is the spark switch when the right end of the vibratory bed is locked and-the left end is free to vibrate. narrow arc of sparks to appear on the dial BI when the contact I36 is engaged with contact I-It is the spark switch I 96 is a switch for causing ,a very spring I. This indicates the angular position oi the compensating weight. I41 and I48 are switches for controlling the angular movement oi. the weight I30, and the switches I49 and I50 are the switchesior controlling the linear movement of the compensating weight I30. I5I, see Figure 10, is a switch for an electric light I55. The friction wheel 55 has a collector ring I52 secured to it but insulated from it. A contact I53 bears against the collector ring I52.

The electrical controlling system I The manner in which the balancing machine is electrically controlled, at the will 01' the operator, to determine the unbalance in aspecimen being tested and the proper correction for such unbalance in two selected planes of correction, will beunderstood, by reference more particularly, to the wiring diagram shown in Figure 10, wh ch will now be explained.

I54 designates a source of electric supply from which leads a line I55 to the lamp I55, containing the light switch I5I, grounded at I51. The source of electric supply I54 is grounded at I58.

The switch I45 is in a line I59 which leads to the primary winding of the high tension coil I88 the secondary winding of which is connected with the graduated ring of the angle indicator 5| and the dial hand 59 is grounded as at I50. The line I5I from the switch I45 leads to the contact mechanism I62 at the left hand end of the vibratory frame or bed of themachine and this contact mechanism is groundedasat I53. The switch I44 has a line I54 communicating with the line I59 which leads to the primary winding of the high tension coil I88 the secondary of which is con-v nected with the'angle indicator 5| as before explained, and the other line I55 from the switch I44 leads to the contact mechanism I81 at the right hand end of the vibratory frame, such con tact mechanism being grounded, at I58. The switch I45 has a line I69 communicating with the line I59 which leads to the primary winding of the high tension coil I88, the secondary oi. which is-connected with the angle indicator 5| and also has a line I10 which leads to the contact arm I which cooperates with the revoluble contact I35on the insulated collar I35. The contact I35 is grounded as at "I.

A line I12 leads from the source of electric supply I 54 to one side of the switches I41, I48, I49 and I50. The other side of the switch I41 I0 I. with the electromagnets I02, it being remembered that these electromagnets control the linear movement of the compensating weight I30, see Figures 8 and 3 while the angular setting is con- .trolled by electromagnets 84 and 85. The electrom'agnets IOI and I02 are connected byline I15 with the contact I53 which rides on the collector ring I52 which passes current to electromagnets 12 which are grounded at I15. The switch I49 communicates by line I11 to the electromagnets 85 which control the angular setting of the screw II5 with respect to the rotation axis of the body being twted. These electromagnets 85 are shown Grounded as at. I18. Theswltch I50 communicates by line I19 to the electromagnets 84 which control the angular setting of the screw I I5' and compensator weight I30 with respect to the rotation axis of the body being tested. These electromagnets 84 are shown grounded as at I 80. The line I55 which leads from thegsource of electric supply I54 to the light also leads by line I8I to 1 vibrating bed is locked at either support with the r other end unlocked. The actual weights required for correction of the part to be balanced depend on the locations of the planes of such part where corrections are to be made. With either end of the vibrating bed locked on its pivot and with the'other end unlocked, the compensator is adjusted for each end until it counterbalances the unbalance in the part being tested. Both readings on the compensator are assumed to be ounce inches and in this diagram it is assumed that corrections for unbalance are to be made in two planes located over the two pivots J and H and it has been assumed that in each case the unbalance reading is 10 ounce inches which is the product of weight and radius.

The operation will now be apparent to those skilled in this art and is as follows.

roller supports 2I are adjusted so that the rollers 23 of each pair are adjusted to suit the diameters of hearings in the part to be balanced. They are,

then looked in position. The cross bars I9 are clamped to the rods I4 of the vibratory bed as are also the clamping devices 84 in case the center guide is employed. The specimen to be tested, such as, ,ior example, the crank shaft illustrated in Figure 1, is now placed on the rollers as shown and connected with the driving pins of the face plate 54 which is in the form of an adapter ring 40 so that the specimen is now in driving'connection' with the electric motor which drives the pulley 52 by means of the belt 53.

The present machine is designed to operate at a comparatively low speed which is different from 45 thecritical speed.

The normal vibrating period of the vibratory unit, with the specimen to be balanced in position and the spindle at rest, should be-not less than 10% higher than the speed of rotation oi the machine. The normal vibrating period is regulated by first touching the vibratory unit to cause it to vibrate naturally andthen counting the number oi vibrations over some given period oitime by noting the frequency 01' sparking on the dial.' 55

Then raise or lower the cross bar 1, see Figures 1 and 5, until the natural period of vibration is at least 10% higher than the speed at which the machine will be operated. This'setting of the cross bar 1 can vary as-one setting will take. care of 0 some diflerence in weight of the specimen to be balanced without aflecting the accuracy of roadings for angular position of unbalance.

The next step is to adjust the spark contacts. This is done by locking one end of the machine 65 on its pivot and releasing the oppasiteend by operating the knurled handles 31. Then operate the knurled handle 48 at the released end until the, spark appears on the dial 51. Turn the same handle 48 rearwardly until the spark 7 just disappears. The spark gap is thus adjusted for each contact mechanismin the same manner locking the pivot at one end and releasing it at the end at which the adjustment oi the contact is to be made. 75

aocaaca without reversing or removing the specimen from' the machine.

Assumingfirst that the right end reading is to be taken, the left end handle 31, see Figure 5, is locked so that the ball QI is in the recess 53 and the pivotal connection at the right end is released so that the right end is now free to vibrate. The motor switch I85 is now actuated causing the specimen to revolve.

The switch hit is now closed, closing the circuit through lines I65, I65 and I58, coil I88 and line I8I so that a series of sparks will appear on the dial hand 59 and the ring 60. The center of the arc of these sparks indicates the angular position of unbalance at the right end of the specimen under test. The switch I id is now opened and the switch I56 closed. This 'closes the circuit through line I8I, coil I88, lines I59, I69, I18, contact I36, and spring contact blade MI, and a very narrow arc of sparks'appears on dialfil, the center of which indicates the angular position of the compensating weight I38. The an ilar position of the compensating weight is now shifted by operating alternateiythe two switches WI and I58 which positions the compensating weight in one angular direction or the other until its position is such that the unbalance can be compensated by the compensating weight.

If the switch I is closed, the circuit is closed through lines I13, I12, thus energizing electromagnet IIII to cause friction wheel NZ to engage friction wheel I I8 to revolve screw I I5 and move the compensating weight in one linear direction in the carrier.

If the switch IE8 is closed the circuit is closed through lines I18, I12 energizing electromagnets I02 which when energized causes friction wheel H0 to be moved into engagement with friction wheel H3 to revolve the screw H5 in the opposite direction and to move the compensating weight in a direction opposite to that in which it moved when switch It! was closed. The closing of the circuit through electromagnets IM or I821halso energizes the electromagnets I2 which form with their armatures I3 an electromagnetic clutch. Now open switch I46 and close switch Mt. Next, operate one or the other of switches Md and I50 until the sparks disappear, at which time the amount and angle of unbalance in the compensator counteracts the unbalance in thespecimen being tested around the fixed pivot. When the switch I49 is closed, the circuit is closed through lines I12, I11 and electromagnets causing friction wheel I88 to contact with friction wheel 58 to partially revolve shaft 85 and the compensator carrier in one direction; and the carrier and shaft are partially revolved in a reverse direction when switch I58 is closed to close the circuit through lines I12, I718 and electromagnets 86 to cause friction wheel I9 to engage friction wheel 56. Now stop the machine at a position where the center of thecompensator weight is at the indicator line on the sight window I86, see Figure 1, and read through the top of the-housing I82 at the sight opening I83. the amount of unbalance as shown in ounce inches on the graduations I28. see Figure 8. Read also the le indicated by the pointer 58 on the graduated dial SI when the machine is stopped in this position. The crank shaft is now marked on the front-over the right and pivot and ma horizontal plane through the axis of the shaft. This indicates the angular location at which material is to be removed at this end to balance the shaft.

The machine is set for a left end reading by locking the right hand end of the vibrating bed to its support by means of the handle 31. at the right end and releasing the left end by operating the handle 31 .of the left spring support 6. The machine is now started by turning the main motor switch I85. Close the switch I58, see Figure 10, which returns the compensating weight I65 and note on the dial 6I the center of the spark are. indicating angular location of unbalance at the left end of the specimen being tested. Turn off the switch I45 and turn on the switch I48 and determine the angular position of the compensating weight by the narrow sparking are on I30 to neutral as to weight. Now turn on switch the specimen being tested around the right and support. .Stop the machine at the position where the center of the compensating weight is at the indicator line on the sight opening I84 of housing I82. With the machine stopped in this position, readthrough the "top sight opening I83 of the housing I82, the amount of unbalance shown on the cylinder I01 of the compensator, and also read the angle indicated. by the pointer 58 on angle indicator 6|. If correction is to be made over the pivots, mark the first on the front over the left hand pivot and in a horizontal plane through the axis of the shaft. This indicates the angular location at which material is to be removed at the left end to balance the shaft.

Referring now to Figure 13, I have already explained that the graduations I29 on the compensator indicate unbalance in ounce inches. Assuming that correction for static and dynamic unounce inches at pivot H. I

' Assuming now that the pivot H is locked and the pivot J is-unlocked and that the same reading,

ten ounce inches of unba1ance at compensator.

Z, the correction that would be required in the crank shaft over the pivot J is determined by Y 8 X XZ- X10-4 ounce inches at pivot J.

determine proper corrections for various read-'- ings from the compensator and these corrections can be specified on the chart in ounce inches or the corresponding depth of drilled holes may be indicated where metal is to be removed to It will, of course, .be

balance the specimen. understood that the unbalance as determined by When balancing a specimen, such as a long crank shaft, where deflection is likely to occur or where the shaft has been slightly misaligned from handling, the center guide brackets should be employed. To adjust this guide bracket .the rollers are moved away a sufilcient distance to clear the shaft and the bracket is clamped in position with a thin spacer plate between the front clamping surface of the bracket base and its cross bar. In this position, adjust and lock the supporting rollers so that they are just in contact with the shaft bearing. The spacer plate is then removed and the clampingscrew tightened. The purpose of exerting this slight downward pressure at the center of the specimen is to prevent the center bearing of the shaft being tested from leaving the rollers of the guide bracket while being rotated. The minimum pressure necessary to hold the center bearing of the specimen to be balanced steady against the rollers of the guide bracket, should be used while the specimen is being rotated at balancing speed.

the specimen being tested is revolved while pivotally supported in determined planes. The vibratory movement in one direction is utilized to visibly indicate by means of an electric spark the angle of unbalance of the specimen. The amount of unbalance in the specimen is compensated for by positioning a compensating weight or value at an angle to the axis of' revolution of the specimen, such compensating weight being revolved during such operation at a predetermined speed relatively to that of the specimen. The unbalance is thus determined as to angle,,amo'unt and linear location at two planes of correction, so that a dynamic couple is formed which will compensate for the unbalance in the specimen-and thus enable one by removing or adding material at such locations to place the specimen in substantially perfect balance.

The compensating mechanism is provided with a variable friction drive controllable at the will of the operator to move the compensating weight inone direction or the other. The compensating mechanism also drives arotatable contact whichis effective to cause a-narrow arc of sparks the arc of sparks which is produced on the angle indicator when the compensator weight is in neutral position. When the weight is properly positioned to compensate for the unbalance in the specimen the sparks disappear from the angle indicator, so that the operator will know that the proper adjustment of the compensating weight has been made to place the specimen in balance.

It will now be apparent that I have devised a new and useful apparatus for balancing rotatable bodies which embodies the features of advantage enumerated as desirable in the state'- ment of the invention and the above description,

and while I have, in the present instance, shown and described a preferred embodiment thereof which will give in practice satisfactory and reliable results, it is to be understood that this embodiment is susceptible of modification in various or sacrificing any of its or a reverse direction. It will be apparent from the foregoing that claim as new and desire to secure by Letters Patent, is:

1. In a balancing machine, a vibratory support for the specimen, means to lock said support to provide either a right or left end pivot for its vibrations, means to revolve a specimen on said support, means to visibly indicate the angle of unbalance of the specimen, a carrier revoluble with the specimen, a compensator weight capable of rectilinear. movement in said carrier at an angle to its axis of revolution, a screw intergeared with said weight, and means to turn said screw in a forward or a reverse direction to position said compensating weight to indicate the mechanical couple of the unbalanced forces with respect to the locked pivot.

2. In a balancing machine, comprising a carrier revoluble in predetermined speed relationship with a revoluble specimen under test, a compensating weight having rectilinear movement in the carrier at an angle to the axis of revolution of the carrier, a screw intergeared with said weight,

a' friction wheel in fixed relation with said screw, I

and electromagnetic means controlled by the operator to drive said friction wheel in a forward 3; In a balancing machine, a compensating device comprising a carrier revolved at a predetermined speed relatively to'the speed of revolution of the specimen under test, a weight car.-'

ried by said carrier and movable thereon, trans-.

versely of the axis of rotation, and means including an electromagnetic clutch controllableat the will of the operator to cause said weight in any angular position it may assume during its revo lution to move transversely'to the axis ofrevolution of the specimen to position it to compensate for and determine the unbalance in the specimen.

4. In a balancing machine, a vibratory support for. the specimen to be tested, means to revolve the specimen on said support, an angle indicator means controlled by the vibratory movement of said support in one direction to visibly indicate on said angle indicator an arc of sparks indicative 4 7 sator. .to be produced on the angle indicator from .5. In a balancing machine, a vibratory support for the specimen to be tested. means to lock said support to provide a right or left end pivot for its vibrations, compensating means revoluble in predetermined relation with the specimen and having a compensating weight, means controllable at the will of the operator to "move saidweight transversely to the axis of the revolution of the specimen, an angle indicator, means controlled by the vibratory movement'of said support and driven in predetermined timed relation with the specimen to produce an arc 'of marks on said angle ndicatorindicative of unbalance in the specimen, and an electrical contact mechanism opened and closed during a revolution of said compensating means and operative to produce an arc of sparks on said angle indicator indicative of the angular position of the compensating weight. 70

6. In a balancing machine, a vibratory support for the specimen to be tested. means to revolve a specimen on said support, means to lock said support to provide a pivot for its vibrations. a

graduated carrier, electromagnetic means to II the specimen on said support, a rotatable carrier,

variable speed driving mechanism driven by saidspecimen revolving means and controllable at the will of the operator to revolve said carrier, a compensating weight mounted in the carrier and movable in the carrier in a rectilinear path at an angle to the axis of revolution of thecarrier, a screw intergeared with said weight, a friction wheel fixed relatively to the screw to revolve it, a pair of driving friction wheels, and electromagnetic means controllable at the will of the operator to cause one or the other of said pair of friction wheels to engage-the friction wheel revolving the screw.

8. Ina balancing machine, a vibratory support for the specimen to be tested, means to revolve a specimen on said support, a variable friction drive including a friction wheel driven in unison with the specimen, and a second friction wheel loosely mounted and adapted to be driven at a different speed from that of said first friction wheel, a carrier driven by said second friction wheel, electromagnetic means controllable at the will of the operator to cause said friction wheels to revolve in unison, electromagnetic means controllable at the will of the operator to cause a variable drive of said second friction wheel by said first friction wheel, a compensating weight in said carrier, and movable in a rectilinear path at an angle to the axis of revolution of the carrier, a screw intergeared with said weight, a friction wheel in fixed relation with the screw, a pair of driving friction wheels, and means to bring one or the other of said pair of friction wheels into engagement with. the friction wheel in fixed relation with the screw.

9. In a' balancing machine, compensating mechanism revoluble in predetermined speed relation with the specimen to be tested, comprising a revoluble carrier having a graduated slot, a compensating weight in said carrier, a member carried by said weight and extending into said slot and having a reference mark, a screw intergeared with said weight to move it in a rectilinear path at an angle to the axis of revolution of the carrier, a friction wheel in fixed relation with the screw, a yoke, a pair of friction wheels fixed to said yoke, and electromagnetic means to move the yoke to bring one or the other of said pair of friction wheels into engagement with said first friction wheel.

10. Compensating mechanism for a balancing machine, comprising a carrier revoluble in determined speed relationship with a specimen under test, and having a slot graduated in ounce' inches, a compensator weight in the carrier movable at substantially right angles to the axis of revolution of the carrier having a shoe in said slot and provided with a reference mark, means to limit the travel of said weight in opposite directions, a screw intergeared with said weight, a friction wheel in fixed relation with the screw, a pair of driving friction wheels, and electromagnetic means controllable at the will of the operator to move one or the other of said pair of friction wheels into engagement with said first friction wheel during the revolution of the carrier.

11. Compensating mechanism for a balancing machine, comprising a carrier revoluble in determined speed relationship with a specimen under test, and having a slot graduated in ounce inches, a compensator weight movable in the carrier having a shoe in said slot and provided with a reference mark, means to limit the travel of said weight in opposite directions, a screw intergeared with said weight, electromagnetic means for controlling the turnlng of said screw in one direction or the other, an electric circuit controlling said electromagnetic means, and means controlled by said screw to indicate the angular position of said compensating weight.

JACOB LUNDGREN. 

